New research indicates stress, mental fatigue and lack of focus all make you susceptible to back injuries during periods of heavy lifting and high stress spinal movements. The study, conducted by the International University of Health and Welfare in Japan and published in the medical journal Spine, used a 3D motion analysis system and four force plates to record kinetic data while inviting subjects to lift a box off the ground. Subjects were required to lift the box while solving arithmetic problems and again without the mental calculations. Interestingly, while solving the math problems the research subjects exhibited poor trunk and pelvis angles for squat and stoop postures which resulted in increased low back load. The researchers concluded that the increased load increased the risk of back injuries and helped to explain the effect of ergonomic demands of lifting tasks, as well as psychosocial factors responsible for the onset of disabling back pain. They recommended that individuals reduce the risks by focusing on the task and avoiding heavy lifting when fatigued or distracted.